Larkspur (Delphinium consolida)
Why we grow it: Part of the buttercup family of flowers, larkspur adds a high-impact, low-maintenance dose of color to your garden with its clustered blooms and colorful petals, typically ranging from white to blueish purple.
Deadly parts: The entire plant, though the young leaves and the mature seeds contain the highest concentration of toxic alkaloids
Toxic toll: These enticing blue growers are definitely just for looking—not eating. Immediately after ingestion, nausea, burning in the mouth, vomiting, and slowing of the heartbeat set in. Seek treatment right away, because six hours is all it takes for this flower to become lethal.